The apartment, known as Apartment 79, sold in 2014 for just under $51 million. The identity of the buyer is unknown because it was purchased through an anonymous limited liability corporation called One57 79 Inc. The LLC took out a loan from Luxembourg-based Banque Havilland in 2015. When the borrower defaulted, the bank forced a sale.

When it opened in 2014, One57 was the shining symbol of a new class of luxury super-towers in Manhattan. Rising to over 1,000 feet, apartments were selling for nearly $7,000 a square foot, largely to overseas buyers. Billionaire hedge funder Bill Ackman and other partners bought the biggest penthouse for just about $90 million.

Yet starting last year, an oversupply of luxury towers and a scarcity of overseas buyers have hurt the top of the market. New development sales fell 25 percent in the latest quarter and units at One57 are selling for discounts of more than 20 percent.

The $51 million apartment is scheduled to head to auction on July 19. Another apartment that sold for $21 million at One57 went to foreclosure auction earlier this month, but there's no word yet on the result.